If schools really cared about anything but profits, then we'd have a mandatory open-source textbook market where academia would be free to create and modify textbooks.

Schools don't write books. Authors write books, and writing a good textbook is hard work, and boring too, compared to other work available to somebody who is competent to write one. I have only written one so far, and would only do it again if paid handsomely. The same goes for revising my first book.

Who is going to write your open-source textbooks? And who is going to pay the authors?

Note: I'm not American, and I acknowledge that the US textbook market is a racket. It is faily obvious from how US publishers try to convince me to switch to their books.